Known gas turbine engines typically include a high pressure compressor having spaced, rotatable blades. A plurality of variable stator vane assemblies are secured to the compressor stator casing and each assembly includes an air foil which extends between adjacent blades. The orientation of the air foils relative to the compressor blades is variable to control air flow through the compressor.
At least one known variable stator vane assembly includes a trunnion bushing partially positioned within a metal jacket. A portion of the air foil extends through the trunnion bushing. The assembly is bolted onto the compressor stator casing. Components of this known stator vane assembly can be removed without removing the top compressor casing and the bushing maintainability and wear life characteristics are good.
Although the known variable stator vane assembly provides certain advantages as explained above, such vane assembly has two possible gas stream leakage paths. The primary leakage path is between the outside diameter of the air foil and the inside diameter of the bushing. The secondary leakage path is between the outside diameter of the metal jacket and the inside diameter of the compressor stator case opening. Such leakage paths can result in an engine performance deficit, which is undesirable.
It would be desirable, of course, to provide a variable stator vane assembly, for use in connection with a high pressure compressor, which eliminates the above described leakage paths. It also would be desirable to provide such a variable stator vane assembly which can be removed without having to remove the top compressor casing.